If you've raced a bike in the past few years, you've probably seen that guy—the guy with the tights—out in the parking lot. He wore the tights in the car on the way to the race—and maybe slept in them last night. As soon as the race is over, he'll pull his bibs off and roll the squeezy fabrics back on. Maybe it's knee-highs instead of tights. Either way, he'll keep that look for hours, from the postrace diner stop right up until he showers as he seeks to recover from the hard efforts of the day. When it comes to compression, he's a true believer. His legs were fresher than anyone else's, and he's recovering faster. Or so he thinks.

For years, doctors have relied on compression stockings to improve circulation in diabetic and bed-bound patients, as well as to treat lymph edema and phlebitis, among other conditions. The idea is fairly simple: Increased pressure on muscles accelerates the flow of blood to the heart by accentuating human physiology. Blood is pumped to the extremities via high-pressure arteries, but it trickles through low-pressure veins located just beneath the skin on its way back. With added pressure, the blood in those latter veins speeds up. Sometime in the 1980s, professional athletes got to thinking: If increased blood flow was good for patients with circulation-related maladies, wouldn't it also benefit them? Soon, racers started regularly slipping out of their newfangled spandex shorts (this was the 1980s) and into women's support hose after races.

Thirty years later, compression garments have become a part of our sport, and are popular among runners, triathletes, and other athletes. Some of the greatest benefits are claimed by pro cyclists who often face demanding travel schedules: "I wear compression gear almost every waking hour, except for when I'm on the bike," says American pro Craig Lewis.

CW-X, Skins, and 2XU, three of the most prominent manufacturers of compression garments, all claim that wearing their tights and socks can improve recovery speed, and, if worn during sports, can boost overall performance. Pros such as Lewis say that they can feel the difference. Ever-increasing numbers of amateur racers—presumably without pro-level travel demands—emulate their heroes by wearing compression garments to the bike shop as well as the race venue. But the question remains: Do athletes get the same benefits from tights as bed-bound patients?

It turns out that what cyclists—even pros—say or believe doesn't necessarily jibe with reality. Science has yet to prove a benefit for cyclists using compression garments for recovery. There is more conclusive evidence regarding compression's benefits during athletic competition, but cyclists seem reluctant to trade their kits for nondescript compression wear. Here we take a look at the facts and fictions surrounding one of cycling's most misunderstood fads.

Dubious Physiological Benefits

There's minimal evidence to demonstrate that compression garments have an impact on recovery for cyclists, despite data showing that they can provide real benefits to runners, says Rob Duffield, PhD, an exercise physiologist at Charles Sturt University in Australia. He has published three compression studies and performed several more for companies that manufacture compression gear. None of his research—or studies performed by others, he says—has convinced him that tight hosiery makes cyclists faster or stronger.

That hasn't stopped some riders from using compression wear, mainly out of a sense that they have nothing to lose. Jeremiah Peiffer, PhD, a competitive cyclist and exercise physiologist at Murdoch University in Australia, regularly wears the garments because he believes in what he calls a "very sound" theory, that increased blood flow will lead to better performance and recovery, even as he admits to doubting the benefits are significant. "It's very hard to find a study that makes a clear claim," he says.

The manner in which a human body propels a bike accounts, at least partially, for why compression may not be effective for cyclists. Pedaling is a concentric motion, which means muscles shorten during exertion. In other types of exercise, including running and plyometrics, muscles lengthen as they activate (eccentric), which can lead to delayed onset muscle soreness (DOMS), a condition that compression garments can help alleviate during recovery. "It's highly unlikely that you'll get DOMS as a cyclist," explains Peiffer, who says that studies performed with runners and other eccentric exercisers have little relevance for cyclists.

So Why Do We Use Them?

Every rule has exceptions, and even if most studies have failed to identify a direct benefit, some researchers have reached different conclusions. A 2008 study published in the International Journal of Sports Physiology and Performance noted that muscles shrouded in compression garments performed ably on less oxygen. Matt Driller, PhD, a researcher with the Australian Institute of Sport, conducted two unpublished studies to measure the effect of compression garments on back-to-back, 15-minute cycling trials, and found that cyclists were better able to overcome fatigue to repeat an athletic performance after wearing compression tights.

Triathletes (who, obviously, also run) are often seen racing in compression gear, but current UCI regulations and unwritten (but influential) style rules keep road racers and those who emulate them from wearing compression gear during rides. Still, many cyclists still utilize them for recovery, claiming benefits above and beyond those the researchers can identify. Remember, science also cannot fully explain how bicycles are able to remain upright.

It's All in Our Heads

It's also possible that compression's real benefit—that cyclists say they feel better after using the garments—can be attributed to the placebo effect, in which people imagine benefits that don't have a physical basis. "There may be a perceptual benefit," Duffield notes. "Athletes race how they feel."

If that's the case, then compression has real value, even if it's purely mental. "Athletes believe in [compression garments], and they like them, so there's a benefit for them," says Duffield. If you're an athlete—cyclist, runner, or triathlete—looking for a psychological boost, they may be worth trying, especially if you frequently travel to ride your bike or often tackle back-to-back days of big mileage. Before purchasing your own compression clothes, consider the science as well as the anecdotal evidence. You may also consider their distinctive looks. If you can stomach wearing tights to your bike shop, around your house, and maybe even in public, it may be worth trying them, and deciding for yourself if there are benefits. Just don't expect miracles.

Fit Is Function

When it comes to compression, one thing is clear: Without a proper fit, you stand no chance of gaining any of the benefits the garments may confer. "Compression gear has to be tight, or it's not going to work," says exercise physiologist Jeremiah Peiffer, who often sees athletes wearing them loose—even baggy. "They should feel uncomfortably tight, not like a pair of cycling shorts." Here's what to look for.

Follow the company's size chart, and when in doubt, choose the smaller option.

Ease on socks and tights carefully, like silk stockings rather than jeans. Grabbing fistfuls of fabric and yanking overstretches the spandex and wears out its squeeze factor faster.

Once on, the fabric should be uniformly smooth and even, with no creases or variations in the weave.

Make sure the foot end fits tighter than the top: Gradient compression, which means more pressure at the feet and ankles than at the thighs, is most effective at moving blood.

Should you shop the medical-supply store?

Surgical stockings (made by Futuro and other companies) cost less than half the amount you'll pay for athletic compression wear, but there are good reasons to pony up for a sport-specific squeeze.

Better FitSkins performed body-mapping research on more than 4,000 athletes, gleaning 800,000 points of measurement from each individual to identify the 400 most significant variations. The results inform the company's broad sizing spectrum, which offers 13 sizes in men's tights alone.

Durability Athletic garments are engineered for repeated use; medical fabrics are less resilient.

Fit Chick: Perception Is Reality

A decade of research has been inconclusive on the performance benefits of using compression garments, but when it comes to the psychological boost they provide, there's no doubt in my mind they're worthwhile. I benefit from compression because it makes my legs feel like they're having a good day—and so even if I'm not measurably faster, I still feel like I'm on my game. Here are three brands I recently put through the paces.—Selene Yeager

Skins RY400 Recovery
In a word: comfy. The Skins sizing system takes your height, weight, and shape into account and delivers a spot-on fit. Plus there's the Memory MX fabric, a special yarn that doesn't become misshappen. I appreciated the knee articulation Skins has added. I know physical therapists who recommend slicing the knees in compression tights to relieve pressure when sitting for long stretches. That's not necessary with these. Overall fit is snug without being oppressive; I could sleep in these. Unlike Skins's travel tights, this model doesn't have foot stirrups. $140; skins.net

2XU Recovery Compression
In a word: springy. 2XU employs an antimicrobial yarn, spun using the company's circular knit technology for a 360-degree stretch that conforms to, and supports, your musculature. I like how I can feel 2XU's gradient pressure at work. The tights are snuggest at the ankles and become slightly less so toward the top of the leg. The result is a pleasant spring in your step, even with the most overcooked legs. My one wish would be for more knee articulation (and maybe foot stirrups), especially for long trips during which I'll be sitting. $160; 2xu.com

Zoot Ultra CompressRx Recovery
In a word: tight. Of the three tights, these were the hardest to shimmy into, especially because my calves are large in proportion tothe rest of my lower body. Once on, however, they hugged every inch of my legs just right. The heavy-duty fabric (70 percent polypropylene and 30 percent spandex) provides the appropriate pressure without impeding your movement as you go about postride activities. I especially appreciated the foot slings that hugged my feet and ankles to prevent swelling. $150; zootsports.com